Bayern had raced into a first-half lead through 17-year-old Lennart Karl, but Mainz, under new coach Urs Fischer, fought back with goals from Kacper Potulski and Lee Jae-sung before Harry Kane's late penalty rescued a point.
Kimmich, speaking after the match, highlighted the areas where he believes Bayern must tighten up. "We've been behind in far too many games recently," he said, reflecting on a run where the Bavarians have repeatedly found themselves chasing the scoreline.
"There are always situations we can defend better, especially set pieces. We need to concede fewer chances, fewer corners, fewer free kicks, fewer throw-ins.
"We definitely must improve that so we don't go behind so often."
His assessment resonated with wider concerns about Bayern's defending. A significant proportion of the goals they have conceded this season have come from set plays, underlining a repeated weakness that opponents have exploited.
The draw against Mainz represented just the second time Bayern have dropped points in the Bundesliga this term, but the manner of the match raised eyebrows given their dominance in possession and chances created.
Kane, who converted from the spot late on, admitted the team were disappointed not to secure all three points. "We had a lot of games in a short space of time, but that's no excuse," he told DAZN, acknowledging that conceding a "silly goal" before half-time shifted momentum in Mainz's favour.
Head coach Vincent Kompany also lamented his side's performance, saying Bayern "had to get more" out of the match and urging his players to be more clinical and resolute at key moments.
Compounding Bayern's defensive concerns, long-time captain and goalkeeper Manuel Neuer was ruled out for the rest of 2025 with a muscle injury sustained during the game, meaning the club will turn to young keeper Jonas Urbig as they head into the winter break.